//https://www.bejson.com/enc/rsa/ help you to create key
String pubKey = """-----BEGIN PUBLIC KEY-----
MFwwDQYJKoZIhvcNAQEBBQADSwAwSAJBALzqlfMadHJyHLj1iHrDT5YMmjBhVIRZ
1gPPKo1majXLD9R59a8Z8Q7eKip5J3hskPQUgNrs9XCtgClkIpu8f6ECAwEAAQ==
-----END PUBLIC KEY-----
""";
